Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
  • C06B45/18—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component
  • C06B45/30—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an inorganic explosive or an inorganic thermic component
  • C06B45/32—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an inorganic explosive or an inorganic thermic component the coating containing an organic compound

Definitions

• Granular propellants for small arms are usually based on nitrocellulose, and may contain, in addition to nitrocellulose, other energetic constituents, stabilisers, glazing agents and such common ingredients. They also usually contain a surface moderant applied to the surface of the grains, the moderant being in greater contion towards the interior of the grain.
• the surface moderants usually employed include methyl centralite (sym-dimethyl diphenyl urea), ethyl centralite, dibutyl phthalate and dinitrotoluene. It is also usual for the propellant to contain a potassium salt, for example, potassium sulphate, to suppress muzzle flash.
• a potassium salt for example, potassium sulphate
• the use of these unsaturated esters in propellants not containing potassium nitrate gives a slight increase in bulk density but no improvement in ballistic efficiency.
• the incorporation ofpotassium nitrate into propellants coated with conventional surface moderant, for example methyl centralite gives a small increase in ballistic efficiency but the effect is offset by a reduction in bulk density which restricts the amount of propellant which can be loaded into a given cartridge.
• ballistic efficiency means the ratio of the kinetic energy of the projectile to the propellant charge weight.
• Preferred esters are those having eight to 20 carbon atoms and preferably they are derived from an alcohol having two to 10 carbon atoms and an acid having three to 10 carbon atoms.
• the ester may, for example, be derived from a polyhydric alcohol and an unsaturated carboxylic acid or from an unsaturated monohydric alcohol and a polybasiccarboxylic acid.
• Convenient polyhydric alcohols include ethylene glycol, triethylene glycol, tetraethylene glycol, hexamethylene glycol, decamethylene glycol,
• a convenient unsaturated monohydric alcohol is allyl alcohol.
• Convenient unsaturated monobasic carboxylic acids include acrylic acid and methacrylic acid and convenient dibasic acids include fumaric acid, maleic acid, itaconic acid and sebacic acid.
• Preferred unsaturated esters include ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, decamethylene glycol dimethacrylate, hexamethylene glycol diacrylate, tripropylene glycol diacrylate, pentaerythritol tetraacrylate, diallyl sebacate, diallyl fumarate, diallyl maleate and diallyl itaconate.
• triethylene glycol dimethacrylate is preferred as it is readily obtainable in stable form, has low vapour pressure and is easy to apply to the propellant grains.
• the unsaturated ester preferably constitutes l to 4 percent by weight of the total propellant composition and the potassium nitrate preferably constitutes 0.4 to 1.6 percent by weight of the total composition.
• the surface moderant may be applied in solution to the surface of the propellant grains but we have found that the concentrated moderant can be advantageously used.
• Penetration of the moderant into the interior of the propellant grains is effected by heating and the heat may advantageously be supplied by injecting steam or mixing hot water with the grains.
• the moderant and grains are mixed by stirring or tumbling, and heated by injection of steam followed by steeping in hot water at 60 to C and drying.
• This water treatment leaches out part of the potassium nitrate originally present in the propellant grains and, if a high potassium content is required in the final surface moderated grain, for example to reduce muzzle flash, a water insoluble potassium compound, for example potassium aluminium fluoride, may be advantageously added to the base composition.
• the improved ballistic efficiency of the surface moderated propellants of the invention compared to surface moderated propellants of the prior art can be realised by varying the quantity of the surface moderant to obtain an increase in projectile velocity for a given powder charge and firing chamber pressure, a reduced charge weight required for a given projectile velocity at a given chamber pressure or a reduced chamber pressure for a given charge weight producing a given projectile velocity.
• propellants are as good in all other respects as surface moderated propellants of the prior art, for example, in bulk density, ballistic stability, ignitability, and high and sub-zero temperature performance.
• the ballistic efficiency is not directly related to the moderating effectiveness of the surface moderant and in order to achieve the improvement in ballistic efficiency it may be necessary to use a somewhat higher weight proportion of moderant than was used in compositions of the prior art.
• the higher proportion of moderant is beneficial in that it reduces the heat of explosion and reduces barrel erosion.
• the invention is further illustrated by the following Examples wherein all parts and percentages are given ted through a piston. From a series of tests the charge weight of each powder (and also the convenient proportion of surface moderant) to give a mean maximum chamber pressure of 20 tons/square inch was deterby weight. 5 mined and the velocity of the bullet using this charge Examples 1, 2 and 3 are not in accordance with the weight was measured by recording the time for the bulinvention and are given for comparison. let to pass between photoelectric detectors placed respectively at 3 and 12 metres from the muzzle of the EXAMPLES barrel.
• the ballistic efficiencies in Table 2 are related to the propellant dough was prepared from the ingredients inprior art powder of Example 1. It is evident from these dicated in Table l and the dough was formed into tuburesults that the surface moderatedpowders made in aclar grains by extrusion through a die of internal diamecordance with this invention using unsaturated esters as ter 1.27 mm provided with a central pin of diameter surface moderants have higher ballistic efficiencies 0.35 mm, and cutting to lengths of 1.27 mm. The so l- 15 than the prior art powders.
• the tubular grains thus formed had an annulus thickness of approximately 0.33 mm and an outside diameter of approximately 0.84 mm.
• a surface moderated granular propellant containing potassium nitrate and, as a surface moderant, an unsaturated ester having at least two ester groups and at least two C C groups in its molecule.
• a propellant as claimed in claim 1 wherein the ester is one having eight to 20 carbon atoms and is derived from an alcohol having two to 10 carbon atoms and an acid having three to 10 carbon atoms.
• ester is an ester of a compound selected from the group consisting of ethylene glycol, triethylene glycol, tetraethylene glycol, hexamethylene glycol, decamethylene glycol, tripropylene glycol, pentaerythritol and allyl alcohol and a compound selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid and sebacic acid.
• ester comprises ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, decamethylene glycol dimethacrylate,
• a propellant as claimed in claim 1 containing a water insoluble potassium compound.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)
• Materials Applied To Surfaces To Minimize Adherence Of Mist Or Water (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Ceramic Products (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Containers And Packaging Bodies Having A Special Means To Remove Contents (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10471045

Family Applications (1)

Country Status (10)

Cited By (1)

Families Citing this family (1)

Citations (3)

• 0
  • BE BE791483D patent/BE791483A/xx unknown
• 1971
  • 1971-11-23 GB GB5445371A patent/GB1357206A/en not_active Expired
• 1972
  • 1972-10-23 ZA ZA727542A patent/ZA727542B/xx unknown
  • 1972-10-27 AU AU48266/72A patent/AU467395B2/en not_active Expired
  • 1972-11-09 US US00304948A patent/US3776787A/en not_active Expired - Lifetime
  • 1972-11-15 NL NL7215437A patent/NL7215437A/xx not_active Application Discontinuation
  • 1972-11-15 CA CA156,550A patent/CA981469A/en not_active Expired
  • 1972-11-22 FR FR7241525A patent/FR2160972B1/fr not_active Expired
  • 1972-11-22 NO NO724271A patent/NO130111B/no unknown
  • 1972-11-23 CH CH1704572A patent/CH574375A5/xx not_active IP Right Cessation

Patent Citations (3)

Also Published As

Similar Documents